Cytotoxic Impact of Licochalcone A-Loaded Solid Lipid Nanoparticles on RIN5F Pancreatic β Cells via Autophagy Blockage

Abstract

Background and Objective: Licochalcone A (LicA), a bioactive chalcone derived from Glycyrrhiza inflata, exhibits broad pharmacological properties but suffers from limited aqueous solubility and suboptimal bioavailability. Solid lipid nanoparticles (SLNs) represent a promising approach to overcome these challenges. The present study aimed to formulate LicA-loaded SLNs (LicA-SLNs), characterize their physicochemical properties, evaluate their cytotoxicity in RIN5F pancreatic β cells, and elucidate the role of autophagy blockage in the cytotoxic mechanism.

Methods: Five formulations (F1–F5) were developed by hot homogenization–ultrasonication. SLNs were characterized for particle size, polydispersity index (PDI), zeta potential, entrapment efficiency, and in vitro release kinetics. Cytotoxicity was assessed via MTT assay, and IC50 values were calculated. Western blot analysis was performed to quantify LC3-II and p62 levels, with densitometric data providing insights into autophagy modulation.

Results: SLNs displayed particle sizes ranging from 150–220 nm with relatively narrow PDIs (<0.3). Entrapment efficiencies exceeded 70% for all formulations, with F3 showing the highest entrapment (82.4 ± 2.5%). In vitro release studies indicated a sustained LicA release over 24 hours, especially for F3, which released 65.1 ± 2.3% of LicA at 24 hours. MTT assays revealed dose-dependent cytotoxicity, with F3 exhibiting the lowest IC50 (19.5 ± 1.8 µg/mL at 24 hours). Western blot demonstrated a decrease in LC3-II and an accumulation of p62 in F3-treated cells, suggesting autophagy blockade.

Conclusion: LicA-SLNs, particularly F3, induced marked cytotoxicity in RIN5F cells via autophagy inhibition. These findings underscore the therapeutic potential of SLN-based LicA delivery for conditions in which modulation of pancreatic β-cell function is desired.